It all comes down to gluten development, Tim! As dough is kneaded/folded or as it rests, gluten strands are able to "develop" which means their bonds able to stretch out further apart and your dough in turn becomes more elastic. As the dough becomes more elastic, it becomes capable of a higher rise and producing a more open crumb (think big holes in the interior of the bread) as well as a more chewy and less crumbly final product.

However, when gluten is overworked, these bonds begin to shear apart and are no longer capable of supporting the structural integrity of the dough. This is why 2-4 stretches is typically the ideal amount in many bread recipes but it all depends on the rise time, initial kneading, types of flour and amount of leavening agent present in the dough. Since bread doughs develop through both kneading and resting (fermenting) there are lots of ways to write a recipe to end up with a high rising and chewy finished product, from no-knead recipes with longer rise times to folded recipes like this one, the recipes that are heavily kneaded (developed) up front and given less rise times. I hope this helps explain a bit about dough development! 

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